A starter motor usually has an electric motor, a output shaft driven by the electric motor, a drive collar movably engaged with the output shaft, a pinion driven by the drive collar, and an elastic member sandwiched between the drive collar and the pinion. The drive collar moves along the output shaft when the output shaft begins to rotate, which causes the pinion to move along the output shaft to engage the flywheel. Further rotation of the output shaft causes rotation of the drive collar and pinion to rotate the flywheel to crank the engine. The elastic member reduces the shock between the drive collar and the pinion as the pinion engages the flywheel. A connection shell surrounds the elastic member and contacts or bears against the drive collar and the output gear to prevent axial separation of the drive collar, elastic member and output gear.
Direct contact between the connection shell and the drive collar and the output gear causes heat and wear of the connection shell due to the relative rotation between the drive collar and the output gear causing rubbing against the shell. This wear can lead to damage of the shell which may lead to axial separation of the output gear from the drive collar which may result in the output gear remaining engaged with the flywheel after the engine has started leading to rapid failure of the starter motor.
The present invention aims to provide a starter motor with a new pinion assembly which can solve the above problem.